Briefly talk to the hiring manager about how you handle underperforming co-workers. You can give an example if you'd like but be sure to keep the mood light and avoid any major negativity or personal bashing.
"If someone is not correctly doing their job, I will bring it to their attention and ask them if they need assistance in any way. Generally this will help the issue. Most people do not do their job right because they feel overwhelmed or they don't know how. By offering help, or training, I can usually eliminate this issue."